Infrared light emitters are frequently used in saunas to provide therapeutic heat to the body without heating the sauna room. This is an efficient way to deliver heat to the body for any therapeutic purpose such as relieving joint pain, improving circulation, and encouraging sweating.
The three categories of infrared light are far infrared, mid infrared, and near infrared. Typically, near-infrared is classified as a wavelength range of 0.7-5 microns, mid-infrared as a wavelength range of 5 to 40 microns, and far infrared as a wavelength range of 40 to 350 microns. These categories have different effects on the human body.
Generally, the longer the wavelength, the less deeply the infrared radiation penetrates into the human body. Therefore, far infrared radiation is good at heating the skin and tissues close to the skin, while near infrared radiation can penetrate more deeply into the human body and reach deeper tissues.
Oftentimes, a need exists for substantial quantities of heat to be delivered deeply into the human body. For example, a patient undergoing hyperthermia treatment may need to raise their core temperature quickly. However, a standard infrared heating element emits near, mid, and far infrared light, and if enough near infrared is delivered to the patient for therapeutic purposes, the far infrared that the heating element also delivers could burn the patient's skin.
It is known that far and mid infrared light is absorbed by water. Water filtering is used in a clinical setting for infrared heating elements used in a hospital setting to filter out the far and mid infrared light and leave only the near infrared light. While this can be useful in a hospital, it is desirable to achieve the same effects in a sauna.
A need exists for a sauna heating element that provides only near infrared light.